SLEEP(1)                  BSD General Commands Manual                 SLEEP(1)

NAME
     sleep -- suspend execution for an interval of time

SYNOPSIS
     sleep seconds

DESCRIPTION
     The sleep command suspends execution for a minimum of seconds.

     If the sleep command receives a signal, it takes the standard action.

IMPLEMENTATION NOTES
     The SIGALRM signal is not handled specially by this implementation.

     The sleep command will accept and honor a non-integer number of specified
     seconds (with a `.' character as a decimal point).  This is a non-porta-
     ble extension, and its use will nearly guarantee that a shell script will
     not execute properly on another system.

EXIT STATUS
     The sleep utility exits 0 on success, and >0 if an error occurs.

EXAMPLES
     To schedule the execution of a command for x number seconds later (with
     csh(1)):

           (sleep 1800; sh command_file >& errors)&

     This incantation would wait a half hour before running the script com-
     mand_file.  (See the at(1) utility.)

     To reiteratively run a command (with the csh(1)):

           while(1)
                   if (! -r zzz.rawdata) then
                           sleep 300
                   else
                           foreach i (`ls *.rawdata`)
                                   sleep 70
                                   awk -f collapse_data $i >> results
                           end
                           break
                   endif
           end

     The scenario for a script such as this might be: a program currently run-
     ning is taking longer than expected to process a series of files, and it
     would be nice to have another program start processing the files created
     by the first program as soon as it is finished (when zzz.rawdata is cre-
     ated).  The script checks every five minutes for the file zzz.rawdata,
     when the file is found, then another portion processing is done courte-
     ously by sleeping for 70 seconds in between each awk job.

SEE ALSO
     nanosleep(2), sleep(3)

STANDARDS
     The sleep command is expected to be IEEE Std 1003.2 (``POSIX.2'') compat-
     ible.

HISTORY
     A sleep command appeared in Version 4 AT&T UNIX.

BSD                             April 18, 1994                             BSD